MONTREAL -- Canada has a widespread and unchecked seafood fraud problem according to conservationist group Oceana, who recently tested seafood samples from retailers across Montreal.

In their study, over a third of the samples they tested turned out to be a different fish than was indicated on the label.

Tuna was escolar; wild pacific salmon was farmed Atlantic salmon; yellowtail was Japanese amberjack.

Besides the obvious health risks these substitutions cause--escolar, for example, can cause nausea and diarrhea--they're also cheaper than the fish they're imitating. Wild pacific salmon can retail for close to $80 a kilogram; farmed Atlantic salmon sells for $35 a kilogram. Furthermore, Oceana said the misrepresentation of seafood could contribute to overfishing.

"When a cheaper, more abundant fish is mislabelled as a more expensive, less abundant one, it can give consumers a perception that the population is healthier than it actually is," the charity said in a press release. "This undermines efforts to stop overfishing, manage fisheries responsibly and protect areas and animals in need of conservation."

For their study, the Oceana tested 90 samples taken from restaurants and grocery stores in Montreal and found 61 per cent were mislabelled in some way. Some species, like yellowtail and snapper, were always mislabelled. 

But the problem extends to more than a few supermarkets and restaurants, according to Oceana. The fishy practice is widespread. Almost half of the 472 samples collected by Oceana across Canada over a two year period were mislabelled.

“We have found farmed fish served up as wild caught, cheaper species substituted for more expensive ones and fish banned in many countries because of health risks masquerading as another species,” said Josh Laughren, executive director at Oceana Canada, in a press release.

The charity wants Canada to institute what they call "boat-to-plate" traceability labelling. 

You can read their latest report--on Montreal's seafood retailers--at oceana.ca